Reduced susceptibility to bovine spongiform encephalopathy prions in transgenic mice expressing a bovine PrP with five octapeptide repeats.

In this work, transgenic (Tg) mice were generated expressing a bovine prion protein containing five octarepeats (BoPrP(5OR)-Tg). After intracerebral inoculation of bovine spongiform encephalopathy (BSE) inoculum, these mice suffered a BSE-like neuropathology but survived longer compared with homologous Tg mice expressing similar levels of a six octarepeat BoPrP protein (BoPrP(6OR)-Tg). De novo-generated five octarepeat (5OR) PrP(Sc) showed no biochemical differences from 6OR-PrP(Sc), and the proteinase K-resistant core (PrP(res)) was biochemically indistinguishable from the 6OR counterpart. Lower susceptibility to BSE is suggested for BoPrP(5OR)-Tg mice, as they were not as efficient at replicating BSE prions from the same natural source inoculum as BoPrP(6OR)-Tg mice expressing similar PrP(C) levels. These results raise the possibility of selecting cattle breeds bearing the 5OR Prnp allele that are less susceptible to prion infection.